The present disclosure relates to a retaining member for preventing a roller and a shaft constituting a drive unit and a gear mounted around such a roller and a shaft from coming off, and an image forming apparatus, such as a copier, a printer, a facsimile machine, and a multifunction peripheral having functions of these, which is provided with such a retaining member.
In conventional image forming apparatuses, such as copiers and printers, a drive transmission mechanism composed of a gear, a shaft, and the like for transmitting a rotational driving force of a drive unit is used to transmit the rotational driving force to rotary bodies such as a photosensitive drum, a developing roller, and the like as driven members. In such a drive transmission mechanism, as a method to prevent a roller, a shaft, and a gear mounted around these from coming off, there has been used a method in which a retaining ring such as an E-ring is mounted around a shaft.
As for image forming apparatuses, there has been an increasing demand for compactness, and this demand puts a strict restriction on the design of the drive transmission mechanism in terms of space. In the method where the conventional retaining member such as an E-ring is used, it is necessary to mount the retaining member from a radial direction of a roller or a shaft, and this disadvantageously requires a space in the radial direction for the mounting, and makes attaching/detaching operations disadvantageously complicated. Furthermore, end parts of the roller or the shaft are exposed, and this disadvantageously allows bearing grease to leak from the end parts.
There is also known a gear retaining structure in which a gear is mounted on a fixed shaft standing on a plate-shaped member made of resin, and an elastically deformable claw-shaped projection is provided projecting from the plate-shaped member, such that a hooked portion of the claw-shaped projection engages with a peripheral edge part of the gear mounted on the fixed shaft.